In the gangster-ridden streets of Naples, any word against the Camorra mafia syndicate is dangerous.

The rebellion by a group of shopkeepers against extortion is unprecedented.

"The fear is huge because they threaten you, your shop, your family," said Raffaele Ferrara, a grocer in the city centre who lives in fear after he and around 300 others decided to say no this year after decades of oppression.

"Every time someone with a suspicious face walks in, you think "˜this is it', even if it is just someone buying a sandwich," Ferrara told AFP.

Around a busy cobbled square, local businesses including butchers, bakeries and grocers have banded together in an anti-racketeering initiative that organizers hope will dent the Camorra's stranglehold on the city.

"They would come by two or three times a year and demand money. Those who didn't pay up were shot in the legs, or beaten up, or stolen from," he said.

The bag men demanded up to 1,500 euros ($1,951) three times a year -- a major cost for small businesses struggling through a deep economic crisis.

The Camorra makes billions of euros a year from drug trafficking, construction contracts and arms smuggling -- a vast operation described by investigative journalist Roberto Saviano in his award-winning book "Gomorrah".

But extortion is the ultimate face of the mafia's power on a local level.

"They can't do without it," said Tano Grasso, a former member of parliament and leader of a national anti-mafia association that has encouraged businesses in Naples to denounce their persecutors for the first time.

"The great thing about the anti-racket is it's not just one person speaking out, it's a whole group. And in a group the risk is gone," he said.

Grasso organizes walks through Naples and its suburbs with the Pietrasanta association to tell others about the campaign and convince them to join.

Those who do will often have to testify in court against their harriers.

The manager of Pietrasanta, Lello Iovine, who named the organization after the first square in Naples to declare itself extortion free, was driven to act after a man turned up in the lobby of the hotel he owns demanding 50,000 euros.

"It was a real shock. He told me I might as well pay up now to put my mind at rest. I went to the police immediately and testified against him, but had to watch my back every time I left the house for a while," he said.

"There are lots of areas of Naples that are still suffering. Until not long ago, there was a lot of social tension in this neighborhood, criminality was embedded. But now we're fighting back and have got a lot of support," he added.

A plaque went up in Pietrasanta square in July declaring it to be an "extortion-free zone". The German consulate has also published a new tourist map showing shops, restaurants and hotels that are not paying racket money.

Antonio Scorza, who runs the local "Griffin Inn" pizzeria, says the decision to join the organisation was not easy, but he is proud of himself.

"The older generations might not have the courage, but we're young. It's time to fight back," he said.

A Molotov cocktail was thrown at the "Griffin Inn" hours before the celebration to mark the square's liberation from the Camorra.

Scorza said he wasn't intimidated, and has had no trouble since.

Since the group banded together, Russo said the extortioners have "disappeared". Three of them are serving nine-year sentences in prison.

There have been big-name arrests too with police capturing fugitive boss Michele Zagaria hiding in a secret bunker near Naples earlier this month and hundreds of millions of euros in Camorra-linked assets seized this year.

But observers say the Naples crime group is far from being in any serious danger. A recent study found the historic port city was the most mafia-ridden in Italy -- far ahead of traditional Cosa Nostra strongholds in Sicily.

In a best case scenario, Grasso said, for every one person who denounces their extortioner, there are 10 who don't.

"We've marked out our position, we've dug a moat, but it's going to take a lot more to win the war," he said.